1. Field of the Invention
The present invention relates generally to systems for monitoring the activity of patients in hospital rooms.
2. The Prior Art
Hospital patients are susceptible to serious injury in slip-and-fall accidents. Elderly patients are especially vulnerable to such accidents while getting out of bed during the night or at other times when hospital personnel are not present. Most such accidents could be prevented if there were a way to alert a nurse as soon as a patient rises from bed so that the nurse could quickly go and assist the patient before the patient has had time to get out of bed and possibly fall.
Several kinds of hospital bed attachments have been devised to alert a nurse if a patient starts to get out of bed. For example, U.S. Pat. No. 4,228,426, issued to Roberts on Oct. 14, 1980, discloses patient monitoring apparatus comprising a switch installed in a pad positioned in bedding underneath the patient. If the patient gets up, the switch contacts open, generating an alarm signal. An electric cable connects the switch to a circuit external to the bed.
U.S. Pat. No. 4,196,425, issued to Williams, Jr., et al., on Apr. 1, 1980, discloses a photocell system wherein a plurality of optical energy emitters and photocells are installed in complementary locations on a hospital bed. If a patient in such a bed sits up or starts to get out of the bed, an energy beam is interrupted and an alarm signal is produced. As with the Roberts apparatus, a cable is required to carry electric power to the energy emitters and to carry the alarm signal from the bed to an external circuit.
Patient monitoring systems such as those disclosed by Roberts and Williams require that a sensing device, such as a switch in a pad, a photocell and optical energy source, or the like, be installed in the bed and that a cable be used to connect said sensing device to an external circuit. This cable poses a hazard in that the patient may trip on the cable while getting out of bed. Also, the presence of an electrically powered device in the bed presents a risk of electric shock. In addition, electrical devices and cables in the bed interfere with making up the bed or moving it for cleaning purposes and often annoy the patient.
It will be apparent from the foregoing that there is a need for a patient monitoring system located remote from the bed and adapted to alert a nurse if a patient gets out of bed. The present invention satisfies this need.